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HOWTO: Fifth- to sixth-gen suspension member conversion

*Standard disclaimer: No liability is assumed, implied or not, by the author for anyone reading this post. Working on your car, or under it, is inherently dangerous to your health and pocketbook. Any risk you take is solely your responsibility.*

This, as the title suggests, is a step-by-step guide to converting the No. 2 suspension arms of a 1990-93 ST/GT/GTS to those of a 1994-1999 Celica ST/GT/GTS (yes, there were sixth-gen GTS available, in Canada). It will also work for those who want to simply replace their suspension arms, as these are often the source of the dreaded and elusive clunk in the rear suspension. I'll also cover what would be required to convert the No. 1 suspension arms to those of a sixth-gen in limited detail at the end of this guide.

The four suspension arms, which run in pairs from the centre of the chassis to the rear axle carriers, are also referred to as lateral links, or occasionally and erroneously as rear control arms. The frontmost of each pair is the No. 1 suspension arm, while the rearward of each pair is the No. 2 arm.

Toe on both the sixth- and fifth-gen FWD Celicas is adjusted via the No. 2 suspension arm. In the fifth-gen, it is managed by an eccentric cam. The downside to this system is that a significant shock may knock it out of alignment. The sixth-gen uses a threaded adjuster on the No. 2 arm, making it a much more robust design. The key to converting between the two systems is replacing the bolt-in-cam connection on the No. 2 arm with a set of plate washers and a 14mm bolt, allowing the sixth-gen arm to mount to the fifth-gen suspension brace.

Note the larger bushing of the left/inner end of the fifth-gen arm (top), which accommodates the cam. Also, apologies for the image quality, 2.0 megapixel camera phones still don't come with particularly good lenses.

For clarity in the following directions: axle carrier refers to the large hunk of metal to which the brakers and wheel hub are attached; suspension brace (identified by Toyota as the suspension member) refers to the portion of the chassis to which the suspension arms connect.

DISASSEMBLY1) Safety
Block the front wheels, loosen the lug nuts on the rear wheels, set the rear of the car on jack stands using the notched jacking points, and remove the rear wheels.

2) Remove the service hole cover
Use the flathead screwdriver to pry out the plastic panel covering the bolts in the suspension brace.

3) Use the penetrating lubricant

a) Strut rod-to-axle carrier nut.
b) Suspension arm-to-axle carrier nut.
c) Along the shaft of the bolt through the axle carrier.
d) On the nuts inside the suspension brace (if the cover is in place, these bolts and nuts are likely in near-pristine condition and require no lubrication).

4) Disconnect the strut rod from the axle carrier
There are no indications I could find that the strut rod has a particular orientation for installation. However, I would suggest if you're re-installing to mark the rod so it may be returned to its original position.

The nut includes a shaped tang which locks the nut in place while you loosen or tighten the bolt. It is often easier, once the bolt is somewhat loosened, to push the bolt back into the hole and spin the nut off the other end.
If you find the bolt is exceptionally difficult to turn, it may help to use the jack to lift the axle carrier.

Optionally, you may remove the strut rod entirely by disconnecting it from the chassis. I did not do so, as it would require removing the brake cable hanger to reach the strut rod bolt (and 18-year-old 10mm bolts on the bottom of a car driven in a temperate rainforest are liable to snap if sneezed upon). However, this would make it easier to move the axle carrier around when dealing with the suspension arms.

5) Remove No. 2 suspension arm

a) Remove the nut from the bolt through the axle carrier
b) Loosen the bolt at the suspension brace enough to remove the toe adjust plate from inside the service hole.
c) Remove the bolt and toe adjust cam.
d) Remove the No. 2 suspension arm from the axle carrier bolt (may require a hammer to push the arm off the bolt).

6) Remove the No. 1 suspension arm

a) Remove the bolt (with integrated washer) from the suspension brace. The nut is flanged to jam in place, but may manage to rotate almost 180 degrees before the bolt itself begins to loosen. The fuel tank does get in the way; the easiest course is to push the bolt head up in order to remove it from the suspension brace.
b) Remove the No. 1 arm from the suspension brace. This may require twisting the axle carrier slightly to get the arm free of the brace.
c) Using the hammer, drive the axle carrier bolt back, then pull the bolt free. The bolt is unlikely to have significant corrosion (if mine didn't manage to rust into the axle carrier, yours probably won't) but a punch might be needed.
d) Remove the No. 1 suspension arm from the bolt.

At this point, your axle carrier should look like this:
Note the gunk and rust in the axle carrier, and in the strut rod bushing.

The No. 2 suspension arm brace:
Again, note the rust.

PREPARATION1) Marking
The suspension arms must be correctly oriented, not only in terms of the inner and outer end, but also front or rear. The arms each have a mark, which should be facing rearward on the outer end of the arm when installed.
These marks are applied with a paint pen and can be wiped off if care is not taken. Brake cleaner will strip the mark off very easily.

I could not find a similar marking on the sixth-gen arms. This may be due to mine being used, but I cannot be certain. However, the sixth-gen arms should be oriented so the longer section is outboard. If you purchase them used, road grime will have built up on the top half of the arm while the bottom side is relatively clean (you can look at your current arms to see a similar buildup).

2) Wire brush
I used the stainless steel wire brush on everything I could manage, nuts and bolts included. A circular brush, particularly if you purchase the Dremel version, fits perfectly into the bushings of the No. 1 arm and the strut rod, both of which I reused. This allows you to clean out any rust while not having to worry about creating irregularities in the shape. I also took the opportunity to clean the axle carrier holes, the outside of the suspension brace, and the rust from the suspension arms.

3) Brake cleaner
Very useful, very dangerous. The rubber bushings of the strut rod and suspension arms could easily be damaged by brake cleaner, so I sprayed it onto shop towels to wipe down the axle carrier and the bushing interiors.

4) Paint
Touch up the suspension arms where paint is missing or repaint them entirely, your choice. Ensure you mask off the bushing so no paint ends up inside.

5) Lubricate
Soak the rubber portions of the strut rod and suspension arm bushings with the silicone lubricant. Also take the time to use the silicone on the uncompressed springs, spring seats, and strut mount.

6) Rough alignment
To make installation easier, make sure the sixth-gen No. 2 arm is adjusted to the same length as the fifth-gen arm.

INSTALLATION1) No. 1 arm to the suspension brace

a) Apply brake grease to the inside of the suspension arm bushing and the shaft of the bolt.
b) Get the bolt into position and lined up between the fuel tank and the suspension brace, then slide the arm into place and run the bolt through.
c) Apply anti-seize to the bolt threads, then slip the nut into place with the flange pointing towards the driver's side of the car. Turn the bolt until it is finger tight only. Remember the mark on the arm must be at the outer end facing rearward.

2) No. 2 arm to suspension brace

a) Apply brake grease to the inside of the sixth-gen suspension arm bushing and the shaft of the 14 mm bolt.
b) Put one of the plate washers onto the bolt, then position the arm inside the suspension brace and run the bolt through with the bolt head to the rear of the car. The washer should centre the bolt inside the cam guide on the brace.

c) Put another plate washer on the end of the bolt, clean any grease from the threads, apply thread locker, then install the nut finger tight.

3) Suspension arms to axle carrier
This should slip together fairly easily, though it might require a little twisting of the axle carrier to get things to line up.

a) Grease the inside of the suspension arm bushings, and the inside of the axle carrier holes.
b) Slide the new bolt through the suspension arms and axle carrier with the bolt head towards the front of the car.
c) Clean any grease off the threads of the axle carrier bolt (shop towel wet with brake cleaner works well, but do not spray the bolt directly), then apply anti-seize to the threads.
d) Install a plate washer and a new nut, again finger tight only.

4) Strut rod

a) Jack the axle carrier up
b) Grease the inside of the strut rod bushings.
c) Install the strut rod to the axle carrier with the nut on the outside (hint: the bolt used in the No. 2 cam is the same size as used to connect the strut rod to the axle carrier, and is likely in near-perfect shape). Apply anti-seize and set finger tight. If you detached the rod only at the axle carrier, you may need to push the carrier forward to get it to line up with the end of the rod.
d) Install the strut rod to the chassis with the nut on the outside. Apply anti-seize and set finger tight. Adjusting the height of the axle carrier will make aligning the bolt hole easier.
e) Reinstall the brake cable hanger; ensure it is correctly aligned by matching the tang on the hanger to the frame, then tighten bolt firmly.

5) Normalise suspension

a) Temporarily install the rear wheels, then lower the car and remove the jack stands.
b) Bounce the vehicle up and down several times to normalise the suspension.
c) Set the car back on jack stands and remove the rear wheels.

6) Torque bolts

a) Torque the suspension brace bolt of the No. 1 arm to 83 ft-lbs (113 N-m). No bracing of the nut is necessary.
b) Torque the brace bolt of the No. 2 suspension arm to 83 ft-lbs (113 N-m). Unless you acquired a 14 mm bolt with an unusually short threaded section, the bolt will project too far to use a socket on the nut.

In this case, use the adjustable crescent wrench to brace the nut against the rim of the suspension brace (hold on to the wrench if possible to prevent it slipping off while torquing the bolt).
c) Gently hammer flat any bends in the rim of the suspension brace.
d) Spray the inside of the suspension brace with the anti-rust paint to seal the scratches caused by the crescent wrench.
e) Torque the strut rod bolts to 83 ft-lbs (113 N-m).
f) Brace the axle carrier bolt with the box wrench on the end of the bolt, against the strut rod. Torque the nut to 166 ft-lb (226 N-m).
g) Install the brace cover.

7) Alignment

a) Install and torque the rear wheels properly, lower the car, remove the jack stands and wheel blocks.
b) Bounce the car, listening for any new noises. A dull clank may indicate one of the arms is installed backwards. This clank may not be apparent until it is driven over noticable bumps.
c) Take the car for an alignment.

FULL CONVERSION WITH CAMBER CONTROL
The following portion is largely theory based on observation, and is not something I have tried nor intend to do. However, let it never be said I'm not thorough.

The idea has been bandied about to give Celicas adjustable camber by using four threaded suspension arms. I cannot see this being particularly effective as the strut rod would restrict or bind angling the wheel out, but I'll be the first to admit my knowledge is limited.

The sixth-gen's suspension arms are connected to the suspension brace by a single carrier bolt essentially identical to the one running through the axle carrier.

This means that the arms all have 14mm bushings, where the fifth-gen has 14mm bushings on the outer ends, 12mm on the inner of the No. 1 arm, and a 12mm bolt inside a cam on the inner end of the No. 2 arm.

To convert the fifth-gen to using all sixth-gen arms would require drilling out the existing holes in the No. 1 arm's brace to accommodate the larger bolt. To accomplish this, it would require either a small acrobat or removal of the fuel tank to aim the drill.

Of course, you'd have to drop the tank to install the sixth-gen bolts anyway. Alternately, you could jury rig the larger bolts into the No. 1 suspension arm much as was done with the No. 2 arm.

STRAIGHT FIFTH-GEN REPLACEMENT
The only difference between the guide as written and the procedure to simply replace the fifth-gen No. 2 suspension arms with new pieces is the parts required.

Obviously it would mean buying the fifth-gen arms. Also required would be the eccentric cams (don't bother buying the cam plates, they will be in good condition), the bolts for the cam, and bolts for the strut rod (last one's optional).

Have you had the car aligned yet? Were there any problems getting toe to spec (or preferably, toe out)? I ask because the lateral links of the 92-93 celica are about 3/4" longer than the 90-91. Do you think there'd be enough adjustability in the 6th gen rods to make them be able to work on both the 90-91's and 92-93's?

She lives!!!

And now thrives. Took 3 years and an embarrassing amount of money, but tooooooooootally worth it To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.

I've not had to deal with the 92-93 suspension, though I'd be quite surprised that they were a different length given the suspension brace is as far as I can tell identical.

The sixth-gen arms were already the exact length of my fifth-gen arms. I have not aligned it; haven't had the necessary combination of weather and time to do the other side. However, the car drives perfectly straight and corners properly, better in fact than before. I hope to complete the conversion later this week and then go for an alignment.

EDIT: Alignment after completing the second arm posed no problems. Aside from improved cornering, an unexpected benefit manifested itself; when heavily loaded (three large male passengers) I no longer scrape going over speed bumps. This was demonstrated before the alignment was corrected, so damned if I can explain it.

I've not had to deal with the 92-93 suspension, though I'd be quite surprised that they were a different length given the suspension brace is as far as I can tell identical.

I'm not sure exactly what part of the suspension required the 92-93 rod to be different, but I can say from bad experience (tried to use 92 rod on my 90 for the bushing), that they are definitely different sizes. Unfortunately, I didn't have a camera to document it with.

However, it is good that it is the same length as the 90-91, and hopefully they have enough adjustability to work for the 92-93 folks as well.

She lives!!!

And now thrives. Took 3 years and an embarrassing amount of money, but tooooooooootally worth it To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.

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